A rubber is used as a component of a composite material as produced by adhering the rubber to other material such as metals, fibers, plastics and the like. However, the adhesion of a vulcanized rubber with other material generally requires a few or several steps.
Such vulcanized rubber as an adherent is different from other materials in the point that it contains various species of compounding agents (extenders) such as softening agents, fillers, vulcanization-accelerators, antioxidants (age resistors) and so on. In general, a surface of a rubber may practically be contaminated by bloom of the compounding agents or adhesion of dusting powder or dust. Therefore, when the vulcanized rubber adheres to other material, a process that comprises the steps of roughening the surface of the rubber by means of a sand paper, a wire brush, blast or others, and removing or eliminating shavings of the rubber adhering to the surface with the use of air or wiping out with the use of acetone, toluene or other solvents for rubbers, and adhering the rubber to other material with an interposition of an adequate primer or adhesive, and drying the resultant, is generally employed.
The primer or adhesive may, however, practically contain a solvent, thus adding working-environmental problems or safety problems. Further, these complicated several steps make automation of the process for compounding difficult.
There have been attempts to simplify adhesion steps of a rubber with other materials. By way of illustration, in a production process of a chemical composite of one molding material containing an aliphatic polyamide as a base, and other carboxyl group-containing rubber (Japanese Patent Application Laid-open No. 150439/1990 (JP-A-2-150439)), there is mentioned a technology that insures a strong adhesion by means of the formation of an amide bond in an interface between the rubber and the plastic without an adhesive. Japanese Patent Application Laid-open No. 138144/1991 (JP-A-3-138144) discloses a composite member as produced by bonding a fiber-reinforced polyamide molded article and a vulcanized rubber molded article.
In these composites, however, there is such a great limitation that the rubber component is restricted to a carboxyl group-containing rubber, and that vulcanization of the rubber is limited to peroxide-vulcanization. Further, when such composites are applied to ordinary rubbers as produced by sulfur-vulcanization, the aliphatic polyamide does not adhere to the sulfur-vulcanized rubber. Incidentally, such sulfur-vulcanization is the most popularly employed technology.
Recently, a novel production process of a composite of a vulcanized rubber and a polyamide has been proposed (Japanese Patent Application Laid-open No. 11013/1995 (JP-A-7-11013)). This process is a process for producing a composite comprising a conventional rubber and a polyamide as strongly bonded each other by incorporating a silane compound having a specific structural formula into a standard rubber available in a market. According to this technology, although there is no limitation that the rubber component should be a carboxyl group-containing rubber or a peroxide-vulcanized rubber, the plastic is restricted to a polyamide or a polyamide-containing resin composition, and the silane compound having the specific structural formula has to be incorporated into the rubber.
It is, therefore, an object of the present invention to provide a composite member which does not require a complicated physical and chemical treatment or the use of an adhesive and insures strong or firm bond between a thermoplastic resin and a rubber, and a process of producing the same.
Another object of the invention is to provide a composite member which can be applied to compounding of a combination of a thermoplastic resin and a rubber in a comparatively broad range, and provides a firm bond between the thermoplastic resin and the rubber, and a production process thereof.
It is a further object of the invention to provide a composite member which insures firm bond of even a sulfur-vulcanized rubber with a thermoplastic resin, and a process of producing the composite member.
Yet another object of the invention is to provide a process of producing a composite member which simplifies a complicated process for compounding, and provides a remarkable reduction in cost.